Thanks for the reply.
The computer lab is in the 3rd year of operation and started with a donated MAC and several Windows XP PCs I rebuilt mostly from "genuine junk parts".
I didn't know how well the very first Mint machine would be accepted by the kids but they quickly got used to it and preferred it to the MAC.
Eventually the MAC was retired and as bad things happened to the Windows computers, I installed Mint Gnome (8, 9, and eventually 10) on them.
I find that reinstalling Mint from a live disc is the quickest and easiest way to fix problems with individual computers. I try to keep customization to a minimum - add 5 or 6 websites to the Domain blocker, add Frostwire, and give access to a shared printer.
The internet connection is a CAT5 cable from the network switch , through a wall, and connecting to the DSL router in the locked office next door. On my "maybe, would be nice someday" list would be a computer in the office to use as a firewall for the lab, doing the website filtering there and also logging websites visited so I could adjust the blocked list as needed. In addition, I think it could also be used to block notifications of updates and attempts to install additional software. After youth time is done, I could go in the office, physically bypass the firewall, and do required maintenance.
Of the currently available LMDE and Maya DEs, I think either MATE or XFCE should be familiar enough to the kids and I hope not require a lot of system resources.